This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose is to characterize enzyme defects in patients with known or suspected porphyria and their families. Methods include measurement of porphobilinogen deaminase and porphyrins in erythrocytes, porphyrins and porphyrin precursors (delta-aminolevulinic acid and porphobilinogen) in plasma and urine, and porphyrins in feces. Selected patients are entered in other porphyria research protocols at this and other institutions, including analysis of DNA to identify specific mutations in genes for heme biosynthetic pathway enzymes.